Thanks Michał and Iain for the details. This is indeed the very same problem that I recently fixed in the firefox packages, so I'll replicate the fix for thunderbird.
In the meantime there are thunderbird packages in focal-proposed that were rebuilt after the ones in eoan, so once they migrate to the release pocket (which should happen soon as nothing is blocking) the issue will go away.
Thanks Michał and Iain for the details. This is indeed the very same problem that I recently fixed in the firefox packages, so I'll replicate the fix for thunderbird.
In the meantime there are thunderbird packages in focal-proposed that were rebuilt after the ones in eoan, so once they migrate to the release pocket (which should happen soon as nothing is blocking) the issue will go away.