OONI data suggests that since 2023-11-06 Signal is getting blocked in Russia
explorer.ooni.orgHere's a link to what I believe OP intends to show: https://explorer.ooni.org/chart/mat?probe_cc=RU&since=2023-1...
Thanks! I didn't notice that my link was broken
NOTE: A user on the techlore forum pointed out that other countries show similar results, so it might be an error caused by Signal updating how request are handled (maybe for ddos protection)