Supporting platforms that old comes with a massive amount of headaches. It is hard enough for big teams of applications with high MRR to do, and is near impossible for a FOSS application to do in perpetuity.
Note that i do not expect someone to do free work for me, i just do not consider a 5 year old device "old" enough to be weird for it to be supported - especially when it works just fine.
Apple devs has a smart trick how to declare you to buy new iPhone {n+1} just next day after it out: Apple devs just may decrease performance of your previous iPhone {n} fully remotely without any prompts to you and without your permission.[0]
And such remoted control over users costs only $500M single pay - not too much as for Apple at all.[1]
And it would "OK" if there would no releases with new features... but bug fix releases which is worse.
Instead, team (owner & core members) just dropped & disabled everything, leaving Android 5.x/6.x device owners in frozen state.
Even more, team not proposed itself & ignored any proposition from others to at least support Termux for Android 5.x/6.x in LTS-way.