TL;DR: no. Definitively no.

NTL;R: Okay... let me chew on this.

Lemmy as a whole is definitively more toxic than Reddit

For me, at least, non-contributive ("toxic") [see footnote*] behaviour would be: assumptions (including witch hunting), decontextualisation, "didn't read but still replying lol lmao", insults, "I dun unrurrstand", whining + entitlement, and "chrust me" = "I take you for gullible". And those things happen far, far less in Lemmy than in Reddit.

For the poster complaining about Lemmy, "toxic" would be, instead:

• pedants - pedants are fine as long as context-aware. And even then, I don't recall a single pedant screeching at my L3 broken English here, unlike in Reddit.
• purity testers - this can be interpreted 1000 ways.
• concern trolls - yet another thing far more present in Reddit than here...
• contrarians - "oh no what I say should be put in a holy altar, how do you dare to disagree with MEEEEEE?". Sorry but contrarians are leagues above the sort of circlejerking that you see in Reddit, where you'd get 1000 weaboos screeching because you wrote "animes".
• "ackshyually" - refer to what I mentioned already about context. Those "ackshyually" are caused by decontextualisation, that happens far more often in Reddit.

I know that what I'm going to say is anecdotal, but it's still worth sharing: I see the difference specially because I used to moderate a small Reddit sub, and I mod a Lemmy comm nowadays. People here are more reasonable and contributive; I barely need to intervene here, and even then 99% of the time it's like "don't do that" "okay". In Reddit though? Well.

I was on Lemmy.word for slightly over a month and posted many times across numerous communities and instances, so I definitively gave it my best shot.

Depending on which instances yours federates with, you'll get a different experience. lemmy.world and lemm.ee in special tend to gather Reddit-like critters alongside a few good posters, so instances where behaviour is a bit more monitored (such as beehaw) tend to defederate them.

Also Lemmy has backend issues

I'm no coder to claim that the issues are "backend" or "frontend". Instead I'll say the issues that I see:

• papercuts, like the bell icon staying even after you checked all messages
• a lack of mod tools
• rarely lemmy.ml (the instance that I'm in) slows down.
• In the past it used to show errors and refuse to load, but I don't recall this happening nowadays. ~~And it never showed a downtime banana.~~
• can't cross-instance linking posts in a convenient way

So... come on, the platform works. It has its issues, it's likely worse from lemmy.world due to the amount of posters, but it works.

Bad actors

Name them. Otherwise it boils down to "chrust me". Unless referring to the CSAM event below.

lemmy.world comm being bombarded with CSAM [...] Imagine if a subreddit had to be shut down because of this.

I seriously believe that the approach taken by the lemmy.world admins to close down !lemmyshitpost was more sensible than the actions that I'd expect any Reddit instance (oh wait, there's only Spez's) to take. If the same happened in 2023 Reddit, here's what would likelyhappen:

• subreddit mods ask for help to the admins, "we're being bombarded with CSAM". They hear admin crickets in return.
• mods lock subreddit to avoid the bombardment. u/ModCodeOfConduct forces them to reopen.
• mods eventually give up and leave. The sub becomes unmoderated and attracts paedophiles until you got a full paedo ring..
• the paedo ring grows large enough to get a mod outrage of 9001 subs.
• Spez deletes the sub while making a public announcement, like "WE SNOOS STAND AGAINST PAEDOPHILIA!" (cough former Reddit admin Aimée Challenor cough cough)
• the original userbase of the subreddit has no equivalent community to go to, because unlike in Lemmy you're expected to have a single sub per subject.

and sees an influx of kinder people

Dude. You're in Reddit. That's the pot calling the kettle black. Reddit makes even Faecesbook's community look wholesome in comparison, it's on par with modern Twitter. Lemmy is considerably nicer than Reddit.

And if you still want something nicer there's always Beehaw. I'm being serious - for people who want/need an environment with more monitored behaviour, it's a go-to place. Provided of course that you don't want to eat the cake and have it too, by behaving in a way that you don't want others to, otherwise they'll show you the door.