Adblockers will still be allowed, they will just be crippled a lot. It will probably be the same as the adblocking situation on Safari.
If any 3rd party browser vendor wants to maintain a Chromium fork with Manifest V2, they can do so, but with the risk of code maintenance hell. They would also need an extension store for Manifest V2 extensions. Otherwise V2 extensions needs to be installed manually.
Browser vendors can also create their own separate ad blockers that aren't affected by the changes. For example Brave Shields, Vivaldi adblock, Opera adblock, etc.
By doing that you're wasting bandwidth on all the CDNs that hosts ALL your filter lists. Updating the Quick fixes list should be enough. (Which updates every 5 hours automatically on uBO 1.54).
How to manually update Quick Fixes (Manual updates push back automatic updates.)
Click 🛡️ uBO's icon
the ⚙ Dashboard button
the Filter lists pane
the 🕘 clock icon next to the uBlock filters – Quick fixes list
For example: /?igshid=$removeparam=igshid,domain=instagram.com
For the best performance it's recommended to make sure the parameter is included in the filter as seen above with /?igshid, and with the domain it originated from.
Linux Mint do not use the HWE kernel like Ubuntu. However, be on the lookout for a Linux Mint 21.2 Edge ISO. It's not released yet, but that ISO will use a newer kernel.
If you are on Linux you should be able to create a shell script that change your system color to dark or light depending on the time. On gnome there may even be some extension that do that already.
If you use Windows there may also be options to do the same with task scheduler.
They turn white for me (or green for sticky posts). However, there may be some combination of dark mode and theme setting that I've overlooked. The #app id should have the attribute data-bs-theme="dark" if you use darkly. If your entire system use dark mode it should also work by default if your system tells your browser that you prefer dark themes. (But data-bs-theme will still be set to light unless one go to the settings and change the theme to darkly.)
Rather than manually adding communities, could it be made to fetch active/hot communities from for example: https://lemmy.world/api/v3/community/list?sort=Active ?
Sandbox your browser in a VM or something. Don't use the same browser/VM for banking/personal stuff and everyday browsing. Most browsers will do. (Except Chrome/Edge/Opera/Yandex). Personally I prefer Firefox. LibreWolf can also be an option, but you have to opt-in to see videos with DRM etc. Tor is also an option, but the downsides are captchas and websites that block you.
If you're even more extreme you can also use uBlock Origin in "hard mode" and the no script toggle. That will block JavaScript and prevent websites from connecting to any 3rd parties, anything from tracking servers to CDNs. That will definitely break websites, so you'll have to know how to unbreak them, which can be quite the learning curve for some people.
Why not Chrome/Edge/Opera/Yandex you say? Chrome is owned by an advertising company. Edge tracks you plenty. Opera and Yandex comes from authoritarian states.
Adblockers will still be allowed, they will just be crippled a lot. It will probably be the same as the adblocking situation on Safari.
If any 3rd party browser vendor wants to maintain a Chromium fork with Manifest V2, they can do so, but with the risk of code maintenance hell. They would also need an extension store for Manifest V2 extensions. Otherwise V2 extensions needs to be installed manually.
Browser vendors can also create their own separate ad blockers that aren't affected by the changes. For example Brave Shields, Vivaldi adblock, Opera adblock, etc.