Parent is probably referring to the saga of extension support in FF for Android (it used to support all extensions until around 2019, then it didn't [0], then it did again but only a small number of extensions [1], they only recently got back to supporting a large number, but not all extensions [2])

[0] https://www.ghacks.net/2021/01/21/firefox-for-android-is-sti...

[1] https://blog.mozilla.org/addons/2022/12/15/new-extensions-av...

[2] https://blog.mozilla.org/addons/2023/08/10/prepare-your-fire...