dir auth attempts to fetch a descriptor every minute for every relay with mismatched rsa/ed key

moria1's logs are full of stanzas like this:

May 23 17:57:11.242 [info] handle_response_fetch_desc(): Received server info (body size 8933) from server '154.35.175.225:80'
May 23 17:57:11.244 [info] router_load_routers_from_string(): 4 elements to add
May 23 17:57:11.244 [info] dirserv_router_get_status(): Descriptor from router $2F7A826CC5B7E6D834ECA25E236A1351D389D195~EchoBase at 85.212.41.58 has an Ed25519 key, but the <rsa,ed25519> keys don't match what they were before.
May 23 17:57:11.244 [info] router_load_routers_from_string(): Marking router D3F5ABDFB2F5AED2E3D6C95F270953DEB3FCBC93 as never downloadable
May 23 17:57:11.244 [info] dirserv_router_get_status(): Descriptor from router $878413A9DE5AC497A2A5F200DA163F12D503FD8D~torlink2 at 128.199.242.75 has an Ed25519 key, but the <rsa,ed25519> keys don't match what they were before.
May 23 17:57:11.244 [info] router_load_routers_from_string(): Marking router E3E7039714569018DBF9880D5C4799054F0CE59C as never downloadable
May 23 17:57:11.244 [info] dirserv_router_get_status(): Descriptor from router $B5C45F1FD0DFE044772ED1B34160F6CF49B267EC~e35 at 88.75.214.223 has an Ed25519 key, but the <rsa,ed25519> keys don't match what they were before.
May 23 17:57:11.244 [info] router_load_routers_from_string(): Marking router E95C042AA6EB02AB262568B869A4D014E79EBE9F as never downloadable
May 23 17:57:11.244 [info] dirserv_router_get_status(): Descriptor from router $F94A792CE808F8FE39C80AD17CB2D0802F7B9D90~Void at 95.54.95.153 has an Ed25519 key, but the <rsa,ed25519> keys don't match what they were before.
May 23 17:57:11.244 [info] router_load_routers_from_string(): Marking router D56C3F9C4627222890C0C49543370499AA2D7CD6 as never downloadable
May 23 17:57:11.261 [info] handle_response_fetch_desc(): Received 4/4 router descriptors requested from 154.35.175.225:80

In fact, check out this line:

May 23 17:59:11.167 [info] update_consensus_router_descriptor_downloads(): 16 router descriptors downloadable. 0 delayed; 7180 present (615 of those were in old_routers); 0 would_reject; 0 wouldnt_use; 0 in progress.

(The number '16' is the same number as in #22348 (moved).)

I have a new line, once per minute, for each relay whose keys I think are mismatched.

It looks like I am failing to actually mark the descriptor as undownloadable, or I am failing to stick with my decision once it was marked.