Take a look: https://devanswers.co/problem-php-7-2-phpmyadmin-warning-in-librariessql-count/
Firstly, backup sql.lib.php before editing. Edit sql.lib.php in nano.
$ sudo nano /usr/share/phpmyadmin/libraries/sql.lib.php
Press CTRL + W and search for (count($analyzed_sql_results['select_expr'] == 1)
Replace it with ((count($analyzed_sql_results['select_expr']) == 1)
Save file and exit. (Press CTRL + X, press Y and then press ENTER)