“We’re aware of reports that access to Signal has been blocked in some countries,” Signal says. If you are affected by the blocks, the company recommends turning on its censorship circumvention feature. (NetBlocks reports that this feature lets Signal “remain usable” in Russia.)
Friendly reminder that Signal on Android contains proprietary code (google play services), and the server software is rumored to be closed now and/or not what they are actually using due to a lack of updates for a prolonged period. Of course it’s just a rumor and I have no way to verify that, but thought it was worth mentioning (hope this doesn’t count as FUD).
Molly-FOSS seems to be the preferred mobile alternative client.