Section 121 - two homes?

Hoping to get some insight on what would and what would not be eligible for Section 121 given my circumstance.

In March of 2021 my wife and I closed on our new build house. We fully anticipated being in this house for 15 or more years as the kids grew up. Well in September of 2022 I received a promotion and was asked to relocate to a different state, but based on the job we knew there could be a high potential to be moved back to our state/city of origin. Because of this we decided to rent the house out so that in the event we moved back we can land back in our house and school system, etc. The house has had tenants in it ever since. Fast forward to March of 2024 - my job is looking like I’ll be in the new location for several more years. Not keen on renting we decided to buy a house in our new city, while continuing to have the original house leased. Well, no surprise, it’s not July of 2025 and I have received another promo and am moving back to the original state, but not the same city. This promo is more or less a destination role and in an area we have dreamed of living, so moving back to the original house of origin is out of the picture. Plus we have not enjoyed the renting process.

So the question becomes what is and what is not eligible for section 121? Both have been primary homes in the last 5 years. Both moves were due to relocation. We need to sell one or both of the homes to buy our (hopefully) forever homes. The house we bought last year has appreciated some but the original house bought in 2021 has appreciated a ton. How hard can we expect to be hit in taxes if we sell both homes? Thanks!