Just downgraded to Essential from Preferred Service - is my speed throttled now?

Due to some long-term income loss for our household, we just downgraded our internet service from Preferred to Essential. While I understand that we have dropped from 50mps to 15mps download speeds, I have noticed a significant decrease in even the slowest download speeds. For example, one site I regularly frequent would max at  6-7 mps download, now it barely hit 2 mps.  Is this normal? If I still have 15mps, shouldn't I still get up to 15mps download speeds?

Thanks. in advance!