At work I support both Firefox and Thunderbird.
Although there is no Extended Support Release (ESR) version, the Thunderbird release cycle follows the Firefox ESR cycle. The Firefox 68 update caused issues with automatically creating a new profile. Thankfully, the Firefox 78 update did not cause this same mess.
Thunderbird never experienced this profile nonsense. At work in Debian 10 the update from 68 to 78 went well. Even the stand alone Lightning package was removed without fuss because the extension is now part of Thunderbird.
We had a dependency on one add-on. Fortunately the add-on is supported in 78.
The only anomaly was the 78 version launched in a larger window size than 68. Irritating but fixable.