Steps to reproduce

1. Run hugo: hugo server --disableFastRender
2. Navigate to http://localhost:1313/tags/ and note the output
3. Add tag to a content page, e.g., from tags = ['tag1'] to tags = ['tag1', 'tag2']
4. Navigate to http://localhost:1313/tags/ and refresh. The content will be the same as in step 2. while it is expected it would reflect tag2
5. Ctrl-C hugo server and restart (or run hugo build alongside`)
6. Navigate to http://localhost:1313/tags/ and refresh. Now the content is updated.

What version of Hugo are you using (hugo version)?

$ hugo version
hugo v0.146.7+extended+withdeploy linux/amd64 BuildDate=unknown

Does this issue reproduce with the latest release?

Yes