Looks like a manifestation of the general problem with badge instability:
Related topics
| Topic | Replies | Views | Activity | |
|---|---|---|---|---|
| Travis build badge showing failed | 1 | 696 | June 24, 2020 | |
| Badge doesn't reflect build status and randomly changes when retrieved repeatedly | 4 | 1050 | November 9, 2020 | |
| Wrong build-error / build-passing displayed | 1 | 719 | July 16, 2020 | |
| Do not ignore github issues | 3 | 658 | November 9, 2020 | |
| Build status still "unknown" despite a few builds completed | 4 | 805 | June 8, 2020 |