fix: increase Polygon auto-slippage min (#4327)

* fix: increase Polygon auto-slippage min

* comment

* update percent

src/hooks/useAutoSlippageTolerance.ts

 import { Protocol, Trade } from '@uniswap/router-sdk'
 import { Currency, CurrencyAmount, Percent, TradeType } from '@uniswap/sdk-core'
 import { useWeb3React } from '@web3-react/core'
-import { SUPPORTED_GAS_ESTIMATE_CHAIN_IDS } from 'constants/chains'
+import { SUPPORTED_GAS_ESTIMATE_CHAIN_IDS, SupportedChainId } from 'constants/chains'
 import { L2_CHAIN_IDS } from 'constants/chains'
 import JSBI from 'jsbi'
 import useNativeCurrency from 'lib/hooks/useNativeCurrency'
@@ -54,6 +54,7 @@ function guesstimateGas(trade: Trade<Currency, Currency, TradeType> | undefined)
 }
 
 const MIN_AUTO_SLIPPAGE_TOLERANCE = new Percent(5, 1000) // 0.5%
+const POLYGON_MIN_AUTO_SLIPPAGE_TOLERANCE = new Percent(1, 100) // 1%
 const MAX_AUTO_SLIPPAGE_TOLERANCE = new Percent(25, 100) // 25%
 
 /**
@@ -96,8 +97,19 @@ export default function useAutoSlippageTolerance(
       // the cost of the gas of the failed transaction
       const fraction = dollarCostToUse.asFraction.divide(outputDollarValue.asFraction)
       const result = new Percent(fraction.numerator, fraction.denominator)
-      if (result.greaterThan(MAX_AUTO_SLIPPAGE_TOLERANCE)) return MAX_AUTO_SLIPPAGE_TOLERANCE
-      if (result.lessThan(MIN_AUTO_SLIPPAGE_TOLERANCE)) return MIN_AUTO_SLIPPAGE_TOLERANCE
+      if (result.greaterThan(MAX_AUTO_SLIPPAGE_TOLERANCE)) {
+        return MAX_AUTO_SLIPPAGE_TOLERANCE
+      }
+
+      // TODO(vm): Added because ~30% of Polygon swaps were failing due to exceeding slippage.
+      // The root cause is likely elsewhere, but added for now to reduce failure rate on production.
+      const isPolygon = chainId && [SupportedChainId.POLYGON, SupportedChainId.POLYGON_MUMBAI].includes(chainId)
+      const minAutoSlippageTolerance = isPolygon ? POLYGON_MIN_AUTO_SLIPPAGE_TOLERANCE : MIN_AUTO_SLIPPAGE_TOLERANCE
+
+      if (result.lessThan(minAutoSlippageTolerance)) {
+        return minAutoSlippageTolerance
+      }
+
       return result
     }