Details of the issue Why isn't Flatpak being updated? · Issue #29480 · telegramdesktop/tdesktop · GitHub
Why isn't Telegram being updated?
Telegram was routed to external runners months ago because it takes a lot of resources to build Link jpegli statically by ilya-fedin · Pull Request #951 · flathub/org.telegram.desktop · GitHub.
The maintainer has to comment bot, build to start the build. This is documented in Maintenance | Flathub Documentation