Abstract: We have analyzed the time series of coordinates for 5468 radio sources obtained from geodetic VLBI observations in 1993–2024. We have identified 49 objects whose coordinates change within the range from 6 to 143 mas. We have revealed several types of astrometric instability probably associated with different astrophysical processes in active galactic nuclei. In some cases, the coordinates change rapidly over a relatively short time interval (1–3 years). These peculiarities should be taken into account while compiling the next fundamental astrometric ICRF catalogue. © 2025 Elsevier B.V., All rights reserved.