There are some deprecations in latest version of tracker:

Creation of dynamic property MatomoTracker::$currentTs is deprecated

Also other properties are affected:

• MatomoTracker::$forcedVisitorId
• MatomoTracker::$requestTimeout
• MatomoTracker::$configCookiePath
• MatomoTracker::$visitCount
• MatomoTracker::$ecommerceLastOrderTimestamp
• MatomoTracker::$doBulkRequests
• MatomoTracker::$incomingTrackerCookies

        $this->currentTs = time();
        $this->createTs = $this->currentTs;
        $this->visitCount = 0;
        $this->currentVisitTs = false;
        $this->lastVisitTs = false;
        $this->ecommerceLastOrderTimestamp = false;