If RSSI is good but RSRQ is very bad.
What could be the causes of poor RSRQ & SINR?
Often RSRQ value express PRB utilization.
So how is PRB number?
RSSI includes interference as well.
You are in a location with other cells overlapping.
Check how strong are those cells.
Check the coverage plot.
RSRQ = (N * RSRP) / RSSI
You can understand the link.
There are others cells but not as strong as the serving cell.
Where N is?
Number of RB.