At least several other people are having the same problem here https://support.mozilla.org/de/questions/1214123
Firefox installed from snap doesn’t have this problem https://support.mozilla.org/de/questions/1214123#answer-1104753 so the cause might be some Ubuntu modification.
Curiously, switching the input method from IBus to i.e. XIM fixes the issue https://support.mozilla.org/de/questions/1214123?page=2#answer-1152091
At least several other people are having the same problem here /support. mozilla. org/de/ questions/ 1214123
https:/
Firefox installed from snap doesn’t have this problem https:/ /support. mozilla. org/de/ questions/ 1214123# answer- 1104753 so the cause might be some Ubuntu modification.
Curiously, switching the input method from IBus to i.e. XIM fixes the issue https:/ /support. mozilla. org/de/ questions/ 1214123? page=2# answer- 1152091