When I look around, I see many websites, apps, and forms consist of text-fields that have a grayish frame. Do text fields have any accessibility rules when it comes to frame's contrast?
The first example you show is probably ok (it is hard to tell with a static image as we can't test contrast easily).
The second example is almost certainly not in accordance with WCAG.
The third example is probably not ok either, but yet again hard to tell "at a glance".
There is a guideline that inputs and controls should have a contrast ratio of 3:1 minimum with their surroundings.
You can test colour contrast with an online tool such as WebAims colour contrast checker by inputting the border colour and the surrounding colour and ensuring it is greater than 3:1.
Despite the fact it is hard to tell whether your examples meet minimum standards, I would adjust all 3 of them anyway to increase the contrast with their surroundings as these are minimums, not targets and increased contrast helps everybody (i.e. if you are using your phone in bright light) identify controls easily!