Hello @FreddyAL,
Thanks for your post and happy to help!
In regard to your first point, I can confirm that the limit for property values you can filter on when using 'set contains/does not contain' is up to 300 values at once. In this case, I have filed a feature request for expanding the limit on your behalf.
In regard to your second point, "utm_source=Google" will only be available as a freeform value- unless there are any events in the project where PageType = "utm_source=Google" only. Also, I believe you are trying to show that when you select the freeform “utm_source=Google” value that other values appear in the property selection drop-down, correct?
If so, the values in that drop-down selection menu are going to be the top values seen by Amplitude in the last few days, and only the values you actually select and apply will be filtered on. You can test this by building a chart to test the filters you have applied. Here is an example from the Amplitude demo:
https://analytics.amplitude.com/demo/chart/new/35f4hgj
In this case, the best way to include Page Load events where the Page Type contains "utm_source=Google" is to use the contains or set contains operator and select the "utm_source=Google" freeform value.
I hope this helps! Let us know if you have questions.