why did "Promotional Credit w Trade In" payments stop? -$34.73

Last November, I opened up a line for my wife and she traded in her phone for a "free" upgrade to a Pixel 9. It was free in the sense that I only had to pay the taxes on it and then a promotional credit would be applied each billing cycle to offset the installment charge for the phone. Three billing cycles ago, the statement shows

GOOGLE LLCGGX8B - Installment 3 of 36 for $34.73

followed by a line that says

Promotional Credit w Trade In 3 of 36 -$34.73

For the last two billing cycles the promotional credits stopped so now I only get the "GOOGLE LLCGGX8B - Installment" charge without the promotional credit offset . How did that happen? Did I do something to break the promotional agreement? The only things I've done since last November was:

• downgraded from Unlimited Elite to Unlimited Premium Plus to Value Plus VL in an effort to cut down on costs for 5 lines

• cancel a Device Protection Plan for the Pixel which was automatically signed up for me without my consent

• cancel the "Next Up Anytime feature" for the Pixel which was automatically signed up for me without my consent

Did any of the above actions cause a disruption in the promotional credits or was it something else? Please help me understand what is going on here.