Just tried to upgrade my Fairphone 3+ (not rooted) through the /e/ recovery using ADB Sideload – from /e/OS 1.17-s-dev to e-1.19.1-t-20240113373116-dev-FP3 using the download from https://images.ecloud.global/dev/FP3/ I went this way going from Q to S before, but this time I’m stuck here (I chose to ignore the signature verification failure):
I downloaded the zip from https://images.ecloud.global/dev/FP3/ again on a different computer, but the error(s) remain identical. Am I using an all wrong download?
UPDATE: 
SOLVED by AnotherElk’s reply (see below) 