Hi,
I’m experiencing the same issue – after the update: WordPress critical error.
Downgrading the plugin to the previous version temporarily resolved the issue.
After pulling the website on my localhost, with PHP 8.1, disabling all other plugins except Testimonials, and leaving only TwentyTwenty One theme, these are the debug.log results
[17-Feb-2023 08:15:32 UTC] PHP Fatal error: Uncaught TypeError: Cannot access offset of type string on string in C:\xampp\htdocs\dgl\wp-content\plugins\testimonial-free\src\Frontend\Views\partials\dynamic-style.php:188
Stack trace:
#0 C:\xampp\htdocs\dgl\wp-content\plugins\testimonial-free\src\Frontend\Frontend.php(230): include()
#1 C:\xampp\htdocs\dgl\wp-content\plugins\testimonial-free\src\Frontend\Frontend.php(122): ShapedPlugin\TestimonialFree\Frontend\Frontend::load_dynamic_style(Array)
#2 C:\xampp\htdocs\dgl\wp-includes\class-wp-hook.php(308): ShapedPlugin\TestimonialFree\Frontend\Frontend->front_scripts('')
#3 C:\xampp\htdocs\dgl\wp-includes\class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array)
#4 C:\xampp\htdocs\dgl\wp-includes\plugin.php(517): WP_Hook->do_action(Array)
#5 C:\xampp\htdocs\dgl\wp-includes\script-loader.php(2180): do_action('wp_enqueue_scri…')
#6 C:\xampp\htdocs\dgl\wp-includes\class-wp-hook.php(308): wp_enqueue_scripts('')
#7 C:\xampp\htdocs\dgl\wp-includes\class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array)
#8 C:\xampp\htdocs\dgl\wp-includes\plugin.php(517): WP_Hook->do_action(Array)
#9 C:\xampp\htdocs\dgl\wp-includes\general-template.php(3043): do_action('wp_head')
#10 C:\xampp\htdocs\dgl\wp-content\themes\twentytwentyone\header.php(20): wp_head()
#11 C:\xampp\htdocs\dgl\wp-includes\template.php(783): require_once('C:\xampp\htdocs…')
#12 C:\xampp\htdocs\dgl\wp-includes\template.php(718): load_template('C:\xampp\htdocs…', true, Array)
#13 C:\xampp\htdocs\dgl\wp-includes\general-template.php(48): locate_template(Array, true, true, Array)
#14 C:\xampp\htdocs\dgl\wp-content\themes\twentytwentyone\page.php(12): get_header()
#15 C:\xampp\htdocs\dgl\wp-includes\template-loader.php(106): include('C:\xampp\htdocs…')
#16 C:\xampp\htdocs\dgl\wp-blog-header.php(19): require_once('C:\xampp\htdocs…')
#17 C:\xampp\htdocs\dgl\index.php(17): require('C:\xampp\htdocs…')
#18 {main}
thrown in C:\xampp\htdocs\dgl\wp-content\plugins\testimonial-free\src\Frontend\Views\partials\dynamic-style.php on line 188