Having had Mustard Algae for years, that does not look like Mustard algae.
MA is usually found in areas of the pool that are in shade and are not getting as much circulation. It looks like light brownish/yellowish dirt clinging to the walls. For me, it was the walls on the south side of my pool, towards the west. It also showed up in my hot-tub around the area of my step.
While not claimed for MA, the levels for Green Algae seem to be enough to keep MA as bay in the FC vs CYA charts. Stay at the higher end.
As far as using chemicals like Yellow Out, I tried everything. The only thing that worked was keeping my CYA at the lower end of the TFP chart (30 CYA in my case) and dosing chlorine to keep my FC above the minimum line at the end of the day. And my best suggestion is test pool in the evening and dose as soon as people are done using the pool.
If you HAVE MA, follow the SLAM procedure followed by the Mustard Algae procedure.
Here is an extreme picture of yellow algae