Google Indexing Issue Some of My Page

Dear support team,

My website is new (about 2 months). Google starts indexing some of my pages and posts without any problem. But for some important pages such as our service page, Google doesn’t index them even though I request for index on GSC. I’ve tried url inspect but there’s no error or alerts for the pages. Only the result: Discovered-But Currently Not Indexed.

I’ve rechecked the possible cause of not indexing:
1. Sitemaps are checked, and there’s no block or noindex settings for these pages.
2. My websites are mobile-friendly and have no readability issue on different devices;
3. I also set them as Pillar pages to tell Google they are important pages;
4. I also set the canonical url for some of these pages.
5. I’ve also keep our content unique so there’s no low quality content in my site;
6. We also run Google Ads campaigns for these unindexed yet pages, there’s no errors or alerts, too;
7. The weirdest thing is: I submit sitemap to bing as well, and these pages can be indexed by bing without any issue.

The time I heard of your RankMath plugin, I was excited thinking this headache can be soon resolved. But after trying, the issue remains the same. The not indexed links are stilled there.

Please advise what I can do to get this solved. Thanks
Jasmine