Op-amp overloaded

Hi! I am having trouble with a commercial filtering board made with operational amplifiers; here a part of the documentation:
"Due to the low cut-off frequency, the baseline restorer takes some time to stabilize after switching on the amplifier or after replacing the MEA. One to two minutes are quite normal. During this time, the filter amplifier input will be overloaded and you will see only a straight line with very low noise. This is considered a normal behaviour and should not trouble you"
DO you know what does it mean "input overloaded"?
Thank you

It kinds goe slike this, If you have an amplifier with a gain of 2, then 10 mV may become 20 and 0.5 V may become 1V, but a 10 V input may not become 20 V because the supply is limited to 15 or so. In this case any input >7.5V clamps the output at 15 V. (simplified)

There are other types of overloads too, like the common mode voltage is exceeded, but lets not look at that just yet.

Another way to say the "input is overload" is to say the "output is saturated" or at the maximum.