It seems Moodle does not suggest updates for plugins that have new version if those versions are not specified compatible with that new Moodle version.

After upgrading Moodle from 3.11 to 4.3, several plugins did not show up as updatable even though they had more recent versions. This caused trouble, for example, with the JSXGraph filter and JazzQuizz. For both, versions had been released that were compatible with Moodle v4.2 but not specifically with v4.3 as well. After manually installing the most recent versions of these two plugins they worked again.

I can see that it is not optimal to run plugins under Moodle 4.3 that were only deemed compatible with 4.2. But isn't it worse to let Moodle 4.3 run with plugin versions for Moodle 3.11? So I would suggest to make Moodle suggest plugin updates even though they might not have been tested with the latest Moodle version, as they still have a higher probability of functioning than even older plugin version.

Of course, I guess the best way to avoid these issues would be to check plugin compatibility before upgrading Moodle (via Git) to the most recent version.