diff --git a/src/Carbon/CarbonInterval.php b/src/Carbon/CarbonInterval.php
index bbff99fc74..ef01f88afe 100644
--- a/src/Carbon/CarbonInterval.php
+++ b/src/Carbon/CarbonInterval.php
@@ -288,12 +288,15 @@ class CarbonInterval extends DateInterval implements CarbonConverterInterface
      */
     protected ?CarbonInterface $endDate = null;
 
+    protected ?array $initialValues = null;
+
     /**
      * Set the instance's timezone from a string or object.
      */
     public function setTimezone(DateTimeZone|string|int $timezone): static
     {
         $this->timezoneSetting = $timezone;
+        $this->checkStartAndEnd();
 
         if ($this->startDate) {
             $this->startDate = $this->startDate
@@ -316,6 +319,7 @@ public function setTimezone(DateTimeZone|string|int $timezone): static
     public function shiftTimezone(DateTimeZone|string|int $timezone): static
     {
         $this->timezoneSetting = $timezone;
+        $this->checkStartAndEnd();
 
         if ($this->startDate) {
             $this->startDate = $this->startDate
@@ -749,6 +753,8 @@ public function original()
      */
     public function start(): ?CarbonInterface
     {
+        $this->checkStartAndEnd();
+
         return $this->startDate;
     }
 
@@ -759,6 +765,8 @@ public function start(): ?CarbonInterface
      */
     public function end(): ?CarbonInterface
     {
+        $this->checkStartAndEnd();
+
         return $this->endDate;
     }
 
@@ -1086,6 +1094,7 @@ public static function diff($start, $end = null, bool $absolute = false, array $
 
         $interval->startDate = $start;
         $interval->endDate = $end;
+        $interval->initialValues = $interval->getInnerValues();
 
         return $interval;
     }
@@ -2101,6 +2110,7 @@ public function toPeriod(...$params): CarbonPeriod
      */
     public function stepBy($interval, Unit|string|null $unit = null): CarbonPeriod
     {
+        $this->checkStartAndEnd();
         $start = $this->startDate ?? CarbonImmutable::make('now');
         $end = $this->endDate ?? $start->copy()->add($this);
 
@@ -2537,6 +2547,8 @@ public function total(string $unit): float
             throw new UnknownUnitException($unit);
         }
 
+        $this->checkStartAndEnd();
+
         if ($this->startDate && $this->endDate) {
             return $this->startDate->diffInUnit($unit, $this->endDate);
         }
@@ -3237,4 +3249,21 @@ private function handleDecimalPart(string $unit, mixed $value, mixed $integerVal
             $this->add($unit, $floatValue - $base);
         }
     }
+
+    private function getInnerValues(): array
+    {
+        return [$this->y, $this->m, $this->d, $this->h, $this->i, $this->s, $this->f, $this->invert, $this->days];
+    }
+
+    private function checkStartAndEnd(): void
+    {
+        if (
+            $this->initialValues !== null
+            && ($this->startDate !== null || $this->endDate !== null)
+            && $this->initialValues !== $this->getInnerValues()
+        ) {
+            $this->startDate = null;
+            $this->endDate = null;
+        }
+    }
 }
diff --git a/tests/CarbonInterval/TotalTest.php b/tests/CarbonInterval/TotalTest.php
index 77e760b0a1..e32651b782 100644
--- a/tests/CarbonInterval/TotalTest.php
+++ b/tests/CarbonInterval/TotalTest.php
@@ -280,4 +280,15 @@ public function testWithDiffInterval()
     {
         $this->assertSame(51.0, Carbon::parse('2020-08-10')->diff('2020-09-30')->totalDays);
     }
+
+    public function testAlterationAfterDiff()
+    {
+        $t1 = Carbon::now();
+        $t2 = $t1->copy()->addMinutes(2);
+
+        $p = $t1->diffAsCarbonInterval($t2);
+        $p->addSeconds(10);
+
+        $this->assertSame(130.0, $p->totalSeconds);
+    }
 }