Pretty much what others have already said.
You're probably missing something in your cleaning and sanitation regimen. You can't sanitize what isn't clean in the first place.
The cold side, the equipment that touches your cooled wort or beer, is the most prone to infections. As mentioned above, even the valve on your kettle although it gets hot, may still harbor bugs.
Most of us clean with PBW, Oxiclean, or washing soda dissolved in warm or hot water. Soak and scrub all surfaces that will touch your cooled wort or beer using a scratch free nylon brush, sponge or a rag to thoroughly wipe and
clean. Pay special attention to corners, crevices and other places where bugs and dirt can hide, such as in threads and valves.
Then dump or save your cleaning solution, rinse well. Sanitize (Starsan!) right before you're filling them or come in contact with wort or beer. The foam that clings to the equipment keeps it sanitized.
Bucket lids can be a bug trap, especially the groove, and the top is not easy to clean and sanitize either. Have you lifted the lid several times during the fermentation? If so, something could have entered your bucket, even by air. Always mop or spray the lid, especially around the rim area, with sanitizer before lifting the lid, or better yet, leave it on, for more than just this one reason.
It looks like the headspace (above your beer) in that bucket is very large. That can cause trouble too.
I use my cheap plastic fermenting bucket valves about 10 times then I toss them in a concentrated hot solution of PBW. I work the valve every 5 minutes for an hour then let it sit and soak all night long. Rinse well, starsan soak it, and good as new.
Those plastic bucket valves pull or push apart after a brief soak in hot water. The main body consists of two 3/4" barrels that turn into one another. Now you can use a brush to clean them properly, and they're easier to sanitize that way too, assemble wet. No need to keep working them for an hour.