WhatsApp update loop with unsupported iOS version

When I start WhatsApp on iPhone the app is telling me that the version is expired and I must update it on AppStore. Visiting AppStore the version shown is 25.7.77. The banner on top says I need iOS 15.1 or later to install it. When I press "update" for the app I got the message telling me that the version needs a more recent iOS, but I can download the last compatible version. Pressing "download" gets in a loop with the same message over and over.

I knew that older iOS version would not longer be supported sometimes end of April, but this is quite too early and haven't made the necessary arrangements yet.