ublock was already mentioned couple of times. Additionally this one: https://addons.mozilla.org/en-US/firefox/addon/cookie-autodelete/

Ublock
Imagus mod
Return Youtube Dislike
SponsorBlock for Youtube
Video Download Helper
Zoom Page WE

Are there any tab group extensions that do it similarly to chrome, with collapsible groups in the tab bar?

uBlock Origin

Tridactyl

Consent-o-matic

Ublock origin (activate cloud storage and sync rules between devices!)

Bitwarden

Onetab

Firefox translations

Dark reader

Privacy redirect

This is a switch I made yesterday, but instead of Chrome to Firefox, I switched from Vivaldi (Chrome, but kinda like old Opera) to Floorp (japanese fork of Firefox with focus on privacy and sane defaults).

I got Sponsorblock for YouTube, uBlock Origin for ads and Gesturify for those awesome mouse gestures (my main reason for using an Opera-like).

Sometimes, I use Tampermonkey for misc Scripts on different Pages, so I installed that aswell. But for now, no scripts for Tampermonkey, as I primarily focus on setting it up to be more like Vivaldi.

Other addons are Ghostery for more privacy and Session Buddy to prevent oopsies when playing around with Tabs and windows.

Floorp even has dark mode for bright pages already included in the box.

The only extension I cannot live without other than an adblocker is Mouse Gestures.

Is there a way to do credit card autocomplete on the iOS app? It’s the only reason I haven’t made the switch

It's the an extension for Google Passwords? It's my password manager for all my devices.

I would love to switch to Firefox, but I don't want to open chrome every time I need a to retrieve/save a password.

Cookies: Cookie autodelete or Forget me not

Block site (so you're not sent where you don't want to go)

Wayback Machine (if you use it much)

Audio equalizer (to better understand mumbly / old Youtube audio)

Dark background and light text (so you don't go blind)

Surprised noone mentioned NoScript yet. It requires a bit more user interaction. But if you are worried about privacy and maybe security, it is important to know who is running scripts on your machine.

Panorama Tabs! My favorite tab organizer. Also Dark Reader.

Does having a lot of extensions running slow performance?

This thread is full of good suggestions so here are a few that might not have been mentioned:

• Torrent Control - useful for sending magnet links directly to a variety of clients.
• Offline QR Code Generator - good for quickly sending all sorts of stuff to a phone or tablet.
• Better YouTube Shorts - depends if you like them, but this adds autoplay which I love
• TamperMonkey - extensions for your extensions! Usually site specific.