Question about Arlo Essential Wire-Free Doorbell, white

I have purchased 2 pcs. Arlo Wireless Essential Video Doorbell, white and have noticed that there are two different hardware variants. the first variant: AVD2001Aer1.3 with firmware 1.8.0.0_4_4a16fed_758744c. the second variant: AVD2001Aer1.2 with firmware 1.7.0.0_714_ea3a7e4_e4abf14. The second variant cannot be updated to the latest firmware. Why not? Is it already the end of the line? Why don't I get the product with the same hardware variant? I can already see that the two behave somewhat differently.